Energy saving MDCL

[stan]

A technical question - there are some stations we recognize on the list of stations authorized to use MDCL for their AM broadcasting including KTRH. Any idea if they or others are using it?

AM Broadcasting Energy-Saving MDCL

AM broadcast station licensees may now employ energy-saving Modulation Dependent Carrier Level (MDCL) technologies. These technologies are briefly summarized in the Commission's September 11, 2011 Public Notice. AM stations employing Modulation Dependent Carrier Level (MDCL) control...

www.fcc.gov

 

[rfburns]

You will notice that the majority are 50kw, with a few 5kw stations on the list. I've done one MDCL install a few years back on a Harris 3DX50 and it paid for itself within a year.

 

[SomeRadioGuy]

You will notice that the majority are 50kw, with a few 5kw stations on the list. I've done one MDCL install a few years back on a Harris 3DX50 and it paid for itself within a year.

Way more in AK than i thought.. and i can tell you as a listener, i havent noticed a difference.

 

[boiseengineer]

I'd say most U.S. 50 kW stations are using it. It's been in use world wide long before before the U.S. started allowing implementation. Different types in use.
List I saw (can't find it now of course) even shows a few 1 kilowatt stations running it. Gates-Air has kits for their 10 kW and up transmitters. Nautel NX series, 3kW and above, has Dynamic Carrier Control built in.

 

[Kelly A]

Not that I have the time or interest to pinpoint what's going on, but it seems like stations running MDCL, have noticeably lower modulation density than stations not running it. Was visiting a station the other day with a newer Nautel 50KW running factory MDCL. Either the modulation metering on the front panel touchscreen was really out of calibration compared with the Belar mod monitor in the building, or something else is going on. The Belar shows much lower density and peaks, where the Nautel screen shows the transmitter almost closing the envelope negatives, and peaking close to 124%. And the station just seems quiet as compared with others in the market, except other stations also running MCDL.
If this is the case, is losing modulation density and the ability to punch through the increasing noise floor worth the savings?

 

[xmtrland]

I enable MDCL on a 50KW station that carried Rush when he was alive. If I went into night mode for monitor points or had to run the 5KW transmitter to work on the 50KW during rushes show, the Dittoheads would swamp the poor receptionist with calls asking whats going on. I learned to never do any thing that would disrupt the signal during his show.

So when the station decided to run MDCL I figured if it really affected the signal the Dittoheads would call in asking why the station was interfering with Rushes show. Never got one call from the Dittoheads when I turned on MDCL.

 

[Kelly A]

I enable MDCL on a 50KW station that carried Rush when he was alive. If I went into night mode for monitor points or had to run the 5KW transmitter to work on the 50KW during rushes show, the Dittoheads would swamp the poor receptionist with calls asking whats going on. I learned to never do any thing that would disrupt the signal during his show.

So when the station decided to run MDCL I figured if it really affected the signal the Dittoheads would call in asking why the station was interfering with Rushes show. Never got one call from the Dittoheads when I turned on MDCL.

But one could argue that the overall noise floor has likely increased 30% since Rush left the air back in 2020. That said, KIRO was never a screaming demon when it came to modulation anyway. Same with KOMO, even softer. So likely the old timers that listen to both probably didn't notice compared to other stations with denser modulation like what KJR used to run.

 

[xmtrland]

Rush was not on KIRO or ever was. KJR has been running MDCL for several years now.

 

[Kelly A]

Rush was not on KIRO or ever was. KJR has been running MDCL for several years now.

I never said he was. I was commenting on your mention that you started using MDCL on a station that carried Rush.
My point was; that modulation density seems to have suffered for the sake of utility savings of MDCL. Some of that is transmitter design/quirks, but does the loss of density hurt AM's in an age where terrestrial noise has doubled over twenty years ago?

 

[xmtrland]

Your answer made it sound like he was by mentioning KIRO in your reply. KIRO AM didn't have to push the processing because they billed well and had decent rating when it carried the news talk format.

Since moving the talk format to FM and going into 24 hour sports KIRO AM still bills well, even with using MDCL to help save power.

I had a real world experience with MDCL and an audience that I would expect to complain if it affected their listening experience. They did not complain.

In the future it may make sense to turn off MDCL to over come the background noise on the 50KW stations. But that's not my call. My job is to make the AM station function and stay on the air.

The traditional broadcasting environment is constantly changing good broadcast groups embrace the change and figure out how to implement these changes in the cluster groups. It used to be that all we had to worry about was the feed to the transmitter. Now I have feeds to the transmitter, webcast, video webcast HD channel and translator. Some stations may not have the HD channel, video webcast or translator but they should have at least a good app and webcast.

But back to the MDCL and saving power. It's a tool that broadcasters can take advantage of. It does not affect the sellable signal for the groups I work with, it may affect coverage in Bellingham but thats not Seattle.

Its always good to have a discussion with you, it lets me know that the Kelly we all now and love is still out there enjoying life. I have to tell you I was a little worried when you didn't post for a while on RD.

 

[pclover]

Theoretically, I wonder how much power you could save if you could use SSB with the same level of performance. Not to mention spectrum savings.

Obviously, This can't happen now as back in the day SSB radios were expensive compared to normal AM so it's set in stone now

With that said wonder how normal AM radios would respond to a signal like CHU in Canada uses. They only have one sideband but transmit a carrier. NRC shortwave station broadcasts (CHU) - National Research Council Canada

"The transmission mode, upper single sideband with carrier re-inserted"

 

[boiseengineer]

Theoretically, I wonder how much power you could save if you could use SSB with the same level of performance. Not to mention spectrum savings.

Obviously, This can't happen now as back in the day SSB radios were expensive compared to normal AM so it's set in stone now

With that said wonder how normal AM radios would respond to a signal like CHU in Canada uses. They only have one sideband but transmit a carrier. NRC shortwave station broadcasts (CHU) - National Research Council Canada

"The transmission mode, upper single sideband with carrier re-inserted"

Leonard Kahn had a variation of his AM stereo system called "Powerside" that suppressed (not eliminated) the lower or upper sideband, with full carrier.
KSL 1160 was using the Kahn AM Stereo system and later ran it in the Powerside mode for a while.

 

[Dr. Bob]

I had an experience with MDCL on one station where there was enough listening on the fringe that we did receive complaints when it was turned on. It is interesting that Broadcast Electronics was showing a box at this year’s NAB that could adapt their AM transmitters (all less than 10kW) for MDCL. More 5 kW and 10 kW stations with BE transmitters will be adopting it.

 

[xmtrland]

What power level were you running. I run it only at 50KW.

 

[RadioFan2J3]

Leonard Kahn had a variation of his AM stereo system called "Powerside" that suppressed (not eliminated) the lower or upper sideband, with full carrier.
KSL 1160 was using the Kahn AM Stereo system and later ran it in the Powerside mode for a while.

I had not thought about the Kahn units we had at VOA - Greenville for nearly 35 years or so.

Seems we had at least three units based on Kahn's design, which were used on the Gates HF-50C transmitters, running full carrier and one sideband, with the other sideband suppressed.

My memory is really hazy on this, because I can't remember if there were any of these units at B Site, but I remember them at A Site.

The idea behind them was to allow VOA to use these AM transmitters on the utility band frequencies, feeder transmitters for programming into Europe and Africa VOA transmitter sites, but they really weren't SSB transmitters. With only one sideband, I guess it met the ITU requirements.

Again, going from poor memory cells, I think the basics for the units were the Kahn design, but one of the techs, Art Brown, had made some homebrew units which were used at A Site.

This link may go to the design of these units, but I am not an IEEE member, so I can't get to it without paying:

https://ieeexplore.ieee.org/document/4051049

 

[kevtronics]

Leonard Kahn had a variation of his AM stereo system called "Powerside" that suppressed (not eliminated) the lower or upper sideband, with full carrier.
KSL 1160 was using the Kahn AM Stereo system and later ran it in the Powerside mode for a while.

When 1600 WWRL turned off their Kahn Power-Side in 2012, I noticed a definite increase in selective fading. That's when one of the two AM sidebands fades out, which causes a large amount of distortion on normal receivers using an envelope detector -- sometimes bad enough to make the audio completely unintelligible. But when there is effectively only one sideband to begin with, such as when using Power-Side, this effect is greatly reduced, so the audio remains clear and intelligible during signal fades.

A synchronous detector is immune to selective fading, and what maddens me is that every HD Radio includes one, but none of them seem to use it for analog AM reception, so you get that nasty distortion during fades. Since it's all done by DSP, a few lines of code would've fixed this!

 

[Kelly A]

I had not thought about the Kahn units we had at VOA - Greenville for nearly 35 years or so.

Seems we had at least three units based on Kahn's design, which were used on the Gates HF-50C transmitters, running full carrier and one sideband, with the other sideband suppressed.

That's easily the most Powerside boxes Leonard probably ever sold. I just remember taking one apart and recognized hand built immediately.

 

[davideduardo]

That's easily the most Powerside boxes Leonard probably ever sold. I just remember taking one apart and recognized hand built immediately.

"We" had one at WADO. One of the engineers kept putting it back in the audio chain, and I kept telling them to put it on a catapult and launch it into the wetlands.

 

[Kelly A]

"We" had one at WADO. One of the engineers kept putting it back in the audio chain, and I kept telling them to put it on a catapult and launch it into the wetlands.

That was great advice David. If it were heavier, a Powerside would make a good boat anchor.

 

[SomeRadioGuy]

"We" had one at WADO. One of the engineers kept putting it back in the audio chain, and I kept telling them to put it on a catapult and launch it into the wetlands.

YEET, David... Yeet... lol